1. Field of the Invention
The present invention relates to the production of hydrogen peroxide by the oxidation of methyl benzyl alcohol.
2. Description of the Prior Art
Hydrogen peroxide is an important chemical of commerce which is produced in very large quantities for use in a number of industrial applications. The predominant process used commercially for the production of hydrogen peroxide involves the oxidation of anthrahydroquinone, extraction of hydrogen peroxide and reduction of the resulting anthraquinone to anthrahydroquinone which is reused. This process requires very high capital expenditures in that use of a working solvent with efficient recycle of various process components is necessary.
Substantial efforts have been directed to processes which involve direct combination of hydrogen and oxygen but thus far such processes have not found widespread success.
Hydrogen peroxide has been formed by the oxidation of secondary alcohols. At one time the production of hydrogen peroxide by oxidation of isopropanol was practiced commercially. Other secondary alcohols which have been mentioned as possible starting materials for hydrogen peroxide production include methyl benzyl alcohol and cyclohexanol. See, for example, U.S. Pat. Nos. 2,871,102-4 of Shell Development.
Hydrogen peroxide has also been formed by oxidation of high boiling secondary alcohols such as diaryl methanol, the product hydrogen peroxide being stripped from the reaction mixture during oxidation; see U.S. Pat. No. 4,303,632.
In certain commercial technologies substantial quantities of various secondary alcohols are produced. For example, in the coproduction of propylene oxide and styrene monomer by hydroperoxide epoxidation, methyl benzyl alcohol which is also referred to as alpha phenyl ethanol, 1-phenyl ethanol or methyl phenyl carbinol, is formed and ultimately converted by dehydration to styrene monomer. See U.S. Pat. No. 3,351,635.
An improved process for the production of hydrogen peroxide by the oxidation of methyl benzyl alcohol is described in U.S. Pat. Nos. 4,897,252, granted Jan. 30, 1990 and 4,975,266, granted Dec. 4, 1990.
An improved process for the recovery of hydrogen peroxide from methyl benzyl alcohol oxidation mixtures is described in U.S. Pat. No. 4,897,085, granted Jan. 30, 1990.
During molecular oxygen oxidation of methyl benzyl alcohol to produce hydrogen peroxide with acetophenone as a coproduct, organic peroxidic materials such as ethyl benzene hydroperoxide (EBHP), cumene hydroperoxide, tertiary butyl hydroperoxide (TBHP) and ethyl benzene hydroxyhydroperoxide are formed. It is generally advantageous to separate the bulk of the hydrogen peroxide by water extraction from an organic phase which contains acetophenone and other organics. However, due to the distribution equilibrium between the organic and aqueous phases, a small amount of the hydrogen peroxide and the bulk of the organic peroxidic materials remain in the organic phase.
In certain preferred operations, the acetophenone in the organic phase is hydrogenated to methyl benzyl alcohol which can be recycled to the oxidizer or which can be converted to styrene monomer. For safety reasons as well as to avoid process difficulties such as catalyst deactivation, it is important to decompose active oxygen compounds associated with the acetophenone before further processing. It is also extremely important to ensure that active oxygen-containing compounds are selectively converted to acetophenone and methyl benzyl alcohol in order to avoid uneconomic C.sub.8 yield losses.
For removal of trace amounts of H.sub.2 O.sub.2 from the organic stream, various techniques are practiced in the commercial anthraquinone process for the manufacture of H.sub.2 O.sub.2. It has been known, for example, that H.sub.2 O.sub.2 can be catalytically decomposed by various heavy metals such as iron, nickel and copper or noble metals like platinum or palladium. The corresponding metal oxides and hydroxides also act in a similar manner. An essential drawback of this treatment is that the liberated oxygen reacts with hydroquinone present in the solution with renewed formation of H.sub.2 O.sub.2. Also, in this practice, there is no emphasis given on enhancing the recovery of organic compounds which are recycled.
Treatment with solid substances or substances dissolved in water, which are capable of binding H.sub.2 O.sub.2 such as sodium hydroxide, sodium metaborate or sodium carbonate has likewise been known. However, the efficiency of this treatment, which is often accompanied by a chemical change, is very low. It has also been suggested to treat organic solutions with mangano- and ferro-compounds, e.g. with a solution of FeSO.sub.4 or with alcoholic solution or suspension which contains Fe(OH).sub.2. However, apart from the consumption of chemicals, such procedures are not satisfactory because manganese or iron enters into the organic solution, and this results in decomposition in the oxidation step. U.S. Pat. No. 3,107,151 describes use of stannous salts like chloride, sulfate or fluoride for H.sub.2 O.sub.2 decomposition. However, it makes the solution very acidic. U.S. Pat. No. 2,869,989 describes conversion of per-oxygen compounds in the hydrogen peroxide containing oxidation effluent from isopropanol oxidation by thermal treatment of the crude oxidation product at 75.degree. C. to 120.degree. C. for up to an hour.
U.S. Pat. No. 4,994,625, granted Feb. 19, 1991, describes the use of an alumina catalyst to decompose active oxygen constituents in the organic stream which results after separation of hydrogen peroxide from a methyl benzyl alcohol oxidate mixture. Temperatures of 30.degree. to 90.degree. C. are described.
The present invention provides a non-catalytic process for the selective decomposition of hydrogen peroxide and other active oxygen species in an organic stream such as that which results after separation of hydrogen peroxide from a methyl benzyl alcohol oxidate mixture.